JPH05264480A - Method for x-ray fluorescence analysis and apparatus employed therein - Google Patents

Abstract

PURPOSE:To reduce mixing of errors into the analyzing values of the composition and the film thickness by calculating the theoretical intensity of fluorescent X rays of each element while making the generating area of a primary to tertiary fluorescent X rays finite. CONSTITUTION:A control system 22 controls a measuring system 23 and a counting/operating system 20 based on the data from an input/output system 21, the measuring system 23 and the counting/operating system 20. The data from the measuring system 23 is transmitted to the counting/operating system 20, and the counting/operating system 20 calculates, upon receipt, of the data, the concentration of an analyzing element according to the area correcting fundamental parameter (FP) method. The result, calculated in the counting/operating system 20 is transmitted to the input/output system 21 and displayed at a CRT or the like. According to the present FP method, it is noted that the generating area of fluorescent X rays is sequentially larger in the order from the invading area of the entering X rays, the generating area of primary fluorescent X rays, the generating area of secondary fluorescent X rays and the generating area of tertiary fluorescent X rays, and the integration to assign the intensity of fluorescent X rays is carried out within each generating area. Therefore, the composition and the film thickness in a local area can be analyzed correctly.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluorescent X-ray analysis method and an apparatus used for the method. More specifically, the present invention relates to a fluorescent X-ray analysis method using an FP method program capable of local analysis and use for the method. Related to the device. FP according to the present invention
Using the method program, it is possible to perform local analysis of the second phase in the matrix, such as large inclusions in steel materials, or the dispersed phase in ceramics.

[0002]

2. Description of the Related Art The following X-ray fluorescence analysis method is known. When a sample is irradiated with a characteristic X-ray generated from an X-ray tube, a continuous X-ray, or both of them, an element constituting the sample is excited by the X-ray, and a fluorescent X-ray unique to the element is generated. After the fluorescent X-rays are dispersed by a dispersive crystal or a multi-channel analyzer, the intensity is measured, so that the qualitative analysis and the quantitative analysis of the region irradiated with the X-rays can be performed.

The theoretical formula of the fluorescent X-ray intensity shown below is also known. The fluorescent X-ray intensity I (ip) of the element i is a parallel bundle in which the incident X-ray has an infinite cross-sectional area, and when the sample also has an infinite surface area, it is given by the following formula 1. The formula 1 is a theoretical formula derived based on the fluorescent X-ray generation model shown in FIG.

[0004]

[Equation 1]

Here, the first term on the right side represents the primary fluorescent X-ray intensity (I ₁ (ip)) occupied in I (ip), and the second term represents the secondary fluorescent X-ray intensity (I ₂ (ip)). Symbol t, χ _1, χ
₂ , R ₁ , r ₁ , Φ, and ψ are the sample thickness and the element i or the fluorescent X-ray jq that is excited by the incident X-ray to generate the primary fluorescent X-ray ip, as shown in FIG. 2B. The distance between the volume element 1 in which the generated element j exists and the sample surface, the volume element m in which the element i existing that is excited by the fluorescent X-ray jq of the element j and generates the (secondary) fluorescent X-ray ip, It represents the distance from the sample surface, the distance between the volume elements 1 and m, the projection distance of R _{1 on} the sample surface, the incident X-ray incident angle, and the fluorescent X-ray extraction angle. Further, I ₀ (λ), μ (λ), μ (ip),
ρ, Qip (λ), Qip (jq), λ m, and λ _e ⁱ
Is the incident X-ray intensity at the wavelength λ and the X at the wavelength λ, respectively.
X-ray absorption coefficient of sample, X-ray fluorescence ip of sample, sample density, generation efficiency of X-ray fluorescence ip by incident X-ray of wavelength λ, X-ray fluorescence i of fluorescence X-ray jq
It represents the generation efficiency of p, the shortest wavelength of the incident X-ray, and the absorption edge wavelength of the element i. It is known that the equation 1 can be analytically solved if the sample thickness t is sufficiently larger than the X-ray penetration depth (usually 0.1 mm or less), and the equation 2 can be obtained. However,
The contribution of higher-order fluorescent X-rays of the third order or higher is neglected in both Formula 1 and Formula 2.

[0006]

[Equation 2]

[0007] The composition analysis method by the FP method using the above formula 2 which is a theoretical formula of the fluorescent X-ray intensity or the F using the formula 1
A composition / film thickness analysis method by the P method is also known. The quantitative analysis method using the FP method is different from the instrumental analysis method in which "a plurality of standard samples having a matrix similar to the sample" must be prepared, and one standard sample containing the analytical element to be prepared. The feature is that a pure substance of the element to be analyzed can be used as a standard sample. The composition analysis method by the FP method using Equation 2 will be described in detail below.

The generation efficiency Q and the mass absorption coefficient (μ / ρ) in the equation (2) are expressed by the equations (3) and (4) excluding known parameters such as basic physical constants and optical system constants. Represented by. Therefore, the equation 2 becomes the equation 5.

[0009]

[Equation 3]

[0010]

[Equation 4]

[0011]

[Equation 5]

That is, the fluorescent X-ray intensity I (ip) can be predicted if the sample composition W (weight fraction) is determined. Therefore, the sample composition W is the fluorescent X-ray intensity I (i
p), I (jq), ...

[0013]

[Equation 6]

There are various ways to solve the equation 6, but an example is shown in FIG.
It is shown in the flowchart. In the method shown in the flow chart, the sample composition is changed from the initial value, the strength is calculated from two equations each time the change occurs, and the calculation is repeated until the composition having the calculated strength and the actually measured strength is obtained. is there.
Specifically, the content W _i ⁽⁰⁾ of the element i in the same measurement conditions and sample in step 1 inputs the measured intensity I ₀ of X-ray fluorescence ip generated from a known standard sample (ip). In step 2, I ₀ (ip) and W _i ⁽⁰⁾ are used to calculate the element i
The primary content W _i ^{(1) of} is determined.

[0015]

[Equation 7]

Here, I (ip) is the actually measured intensity of the fluorescent X-ray ip generated from the analysis sample. Next, in step 3, a convergence condition (ΣW _i ′ ⁽ⁿ⁻¹⁾ = 1) is introduced. That is, from the (n-1) th order approximate content W _j ′ ^(n-1) of the element j,
W _j obtained in equation (7) instead of the next content W _i ⁽ⁿ⁾ is calculated by the number 8 expression (only first loop of FIG. ^{_{7 W j '(n-1}} )
^{Use (1)} ).

[0017]

[Equation 8]

In step 4, the theoretical intensity of the fluorescent X-ray ip is obtained from W _i ⁽ⁿ⁾ . That is, W _i ⁽ⁿ⁾ obtained by the equation 8
By substituting into the equation ^(2), the theoretical intensity of the fluorescent X-ray ip I ⁽ⁿ⁾ (i
p). Then, in step 5, I ⁽ⁿ⁾ (ip), I
From (ip) and W _i ⁽ⁿ⁾ , the nth-order approximate content W _i ′ ⁽ⁿ⁾ is obtained according to the equation ⁽ 9 ⁾ .

[0019]

[Equation 9]

In step 6, the convergence of the content rate is determined according to the equation (10).

[0021]

[Equation 10]

If Expression 10 is satisfied, then W at that time is satisfied.
_{Since i} ′ ⁽ⁿ⁾ , W _j ′ ⁽ⁿ⁾ ... Are the sample composition to be obtained, the sample composition is output in step 7. If not satisfied, the procedure returns to step 3 to repeat the approximation calculation. As described above, in the FP method based on Formula 1 or Formula 2,
If one standard sample for I ₀ (ip) measurement required by the equation 7 can be prepared, the composition of an unknown sample can be analyzed.

Also, a fluorescent X-ray analyzer equipped with the FP method program is known.

[0024]

However, the conventional F
The mathematical formula 1 which is the theoretical X-ray fluorescence intensity formula on which the P method program is based on is the incident X-ray penetration region, the primary fluorescent X-ray generation region, the secondary fluorescent X-ray generation region, and the higher-order fluorescent X-rays of the third or higher order. It is assumed that the cross-sectional area parallel to the sample surface in the generation area is infinite, or even if the cross-sectional area is finite, the cross-sectional areas substantially match (cross-sectional area ratio of the fluorescent X-ray generation area to the incident X-ray penetration area = 1.000). Therefore, the X-ray micro beam (beam diameter 1
When the four areas do not match (for example, the area ratio> 1.000) as in the local analysis by (00 μm or less), the formula 1
Applying the formula inevitably included an error in the composition and film thickness analysis values.

The present invention has been made in view of the above-mentioned problems, and in local analysis using an X-ray microbeam, each integral fluorescence having a finite cross-sectional area such that the area ratio> 1.000 is obtained by integrating an integral giving a fluorescent X-ray theoretical intensity. PROBLEM TO BE SOLVED: To provide a fluorescent X-ray analysis method using an FP method program in which an error is less mixed in a composition / film thickness analysis value by performing it within an X-ray generation region, and a fluorescent X-ray having this FP method program The purpose is to provide an analyzer.

[0026]

In order to achieve the above object, a fluorescent X-ray analysis method according to the present invention detects the intensity of fluorescent X-rays generated by irradiating a sample with X-rays converted into microbeams, Theoretical fluorescence X of the element in the X-ray irradiation region using the FP method
In the method of analyzing the abundance of elements by calculating the line intensity, the theory of each element is defined as a finite area in which the generation region of primary to tertiary fluorescent X-rays depends on the collimator diameter, the X-ray incident angle and the fluorescent X-ray extraction angle. The feature is that the fluorescent X-ray intensity is calculated.

Further, the fluorescent X-ray analyzer according to the present invention is
The above-mentioned fluorescent X-ray intensity calculation program is installed as a means for calculating the existing amount of the element from the fluorescent X-ray detection intensity.

[0028]

Next, the calculation process of the theoretical X-ray fluorescence intensity in the X-ray fluorescence analysis method according to the present invention will be described with reference to FIG. Figure 2
(A) is a model showing the generation region of primary to tertiary fluorescent X-rays used for developing the FP method program according to the present invention, and (b) is a fluorescent X-ray on which the conventional FP method relies. It is a model for calculating theoretical strength. It should be noted that the symbols used in FIG. 7B have already been described in the prior art, and therefore the description of the symbols is omitted here.

In FIG. 3A, 32 is a primary collimator, 33 is a secondary collimator, Φ is the incident angle of incident X-ray, and ψ.
Indicates the extraction angle of the fluorescent X-ray, and S indicates the irradiation area of the incident X-ray on the sample surface. Area 3 shown with diagonal lines
The symbols 0, 31 and other symbols will be explained in the process of action description.

When the X-ray generated by the X-ray tube or the like is converted into a parallel beam by the primary collimator 32 and is irradiated (incident) on the sample surface, the incident X-ray penetrates into the area indicated by B. Region A is shown as a parallelogram in cross section, but is actually an oblique cylinder. The length d ₀ of the short side of the parallelogram is called the penetration depth of X-rays, and is the wavelength λ of incident X-rays, the weight fraction W _{j of} each element constituting the sample, the sample density ρ, and the element j. Absorption coefficient (μ (λ) /
ρ) _j is used to express as in Expression 11.

[0031]

[Equation 11]

The generation region of the primary fluorescent X-rays excited by the incident X-rays is the region B limited by the sample surface and the dotted line,
Region b contains region a. The distance between the area a and the area b, that is, the distance r ₁ between the area a and the dotted line is expressed by the equation (12). In the equation (12), ip represents a primary fluorescent X-ray, and μ
(Ip) indicates the linear absorption coefficient of the sample for the primary fluorescent X-ray ip. The meanings of the other symbols are the same as those in Expression 11.

[0033]

[Equation 12]

The region where the secondary fluorescent X-rays are generated is a region C defined by the sample surface and the alternate long and short dash line, and the region C includes the regions A and B. The distance between the area b and the area c, that is, the distance r ₂ between the area b and the alternate long and short dash line is given by Expression 13.
In Equation 13, jq represents a secondary fluorescent X-ray, and μ (j
q) indicates the linear absorption coefficient of the sample with respect to the secondary fluorescent X-ray jq. The meanings of the other symbols are the same as those in Expression 11.

[0035]

[Equation 13]

The sample surface and the limited region two by a two-dot chain line shows the generation region of the tertiary fluorescent X-ray, a distance r ₃ number also the distance, that region C and the two-dot chain line in the region D and the region C 11
It can be obtained in the same manner as the formula, the formula 12, and the formula 13.

Equation 1 using the above parameters and symbols
Equation 14 can be obtained by performing the integration in the equation within the generation region of each fluorescent X-ray shown in FIG. The number 14
In the equation, the contribution of higher-order fluorescent X-rays of the third order or higher is ignored, as in the case of the equation (1). For comparison, Formula 1 and Formula 14 are shown side by side.

[0038]

[Equation 1]

[0039]

[Equation 14]

The primary fluorescent X-ray intensity represented by the first term on the right-hand side of the equation (14) is the region 3 indicated by the diagonal line 45 ° to the right of region B.
It is the sum of those generated from zero. This is because, among the primary fluorescent X-rays generated in the area B, only the primary fluorescent X-rays generated in the area 30 are limited by the secondary collimator 33 and the escape depth in the extraction angle direction is r ₁ or less, which is required for observation. Is.

On the other hand, the secondary fluorescent X-ray intensity represented by the second term on the right-hand side of the equation (14) is the sum of those generated from the region 31 indicated by the oblique line of 45 ° to the left of the region C. This is because, of the secondary fluorescent X-rays generated in the area C, only the secondary fluorescent X-rays generated in the area 31 have an escape depth in the extraction angle direction of r ₂ or less and are required for observation.

In the equation (14), the integration range in the sample surface direction is limited by the areas (b) and (c) as described above, but in the equation (1), the integral term indicating the primary fluorescent X-ray intensity is related to the depth direction of the sample. It is integration, and the integration range in the sample surface direction is not limited. Therefore, in Equation 1,
The sample surface area will be treated as substantially infinite. Also in the integral term showing the secondary fluorescent X-ray intensity,
Since the surface area of the sample is infinite as described above in the equation ( ₁ ), the projection distance r ₁ of R _{1 on} the sample surface in FIG. 2B must also be infinite. That is, it is assumed in the formula 1 that the incident X-rays are parallel bundles having an infinite cross-sectional area, and the sample also has an infinite surface area. Therefore, from the wraparound region shown in the model of FIG. The intensity of the generated fluorescent X-ray cannot be treated theoretically.

In the actual measurement, the existence of the wraparound areas, that is, the areas 30 and 31 is determined by the presence of the primary collimator 32.
Has a diameter of 0. Although it can be ignored for several mm or more, 0.1 mm
In the following, the ratio of the cross-sectional area of the X-ray irradiating portion (S in FIG. 2) parallel to the sample surface to the cross-sectional area parallel to the sample surface of the wrap-around region becomes large and cannot be ignored. Therefore,
When a fluorescent X-ray analysis is performed using an X-ray microbeam having a diameter of 0.1 mm or less, the contribution of the fluorescent X-rays generated from the wraparound region is ignored if the conventional FP method program based on Formula 1 is applied. Therefore, the mixing of errors in the composition / film thickness analysis values becomes significant.

[0044]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a fluorescent X-ray analysis method and an apparatus used for the method according to the present invention will be described below with reference to the drawings. FIG. 1 shows an embodiment of an apparatus used in the fluorescent X-ray analysis method according to the present invention.

FIG. 1A shows an optical system of the energy dispersive X-ray fluorescence analyzer, and 10 is a microfocus X-ray tube using tungsten as a target (cathode). A primary collimator 11 is arranged between the X-ray extraction window 10a of the microfocus X-ray tube 10 and the sample surface 12a. One end of the primary collimator 11 is opposed to the X-ray extraction window 10a and the other end is opposed to the sample surface 12a at appropriate intervals, and the primary collimator 11 is viewed from the side of the sample surface 12a.
It is opposed to a at an angle of 45 °. A secondary collimator 11 a is arranged between the sample surface 12 a and the Si (Li) semiconductor detector 13. Secondary collimator 1
One end of 1a faces the sample surface 12a and the other end faces the Si (Li) semiconductor detector 13 with an appropriate interval, and the secondary collimator 11a is a side view of the sample. It faces the surface 12a at an angle of 30 °. The Si (Li) semiconductor detector 13 is connected to the multi-channel analyzer 14. In addition, Si (Li)
The thickness of the X-ray entrance window 13a of the semiconductor detector 13 is 12.7.
Beryllium (Be) of μm is used.

In the optical system of the energy dispersive X-ray fluorescence analyzer constructed as described above, the sample is analyzed in the following process. X-ray extraction window 10 in which the X-rays generated by the microfocus X-ray tube 10 are formed of beryllium foil
It is incident on the primary collimator 11 from a, and the primary collimator 1
A parallel micro-beam is formed at 1 and is incident on the sample surface 12a at an angle of 45 ° (arrow 15). Of the fluorescent X-rays 16 emitted from the sample 12, those incident on the secondary collimator 11a are made into a parallel beam by the secondary collimator 11a, and pass through the thin beryllium layer of the X-ray incident window 13a to form Si.
(Li) Enter the semiconductor detector 13. The incident X-ray (photon) becomes a current pulse having a magnitude proportional to the energy of the X-ray at the Si (Li) semiconductor detector 13. The current pulse is amplified by a preamplifier (not shown), converted into a voltage pulse, then amplified and pulse-shaped by a main amplifier (not shown), and then sent to a multi-channel analyzer 14 for wave height analysis. The result of the wave height analysis is displayed on an XY recorder (not shown) or a CRT (not shown) as an energy spectrum on the horizontal axis and an X-ray intensity spectrum on the vertical axis.

FIG. 1B is a block diagram schematically showing the fluorescent X-ray analysis apparatus according to the embodiment. Reference numeral 22 denotes a control system, and the control system 22 controls the measuring system 23 and the counting / calculating system 20 based on information from the input / output system 21, the measuring system 23 and the counting / calculating system 20. The information of the measuring system 23 is transmitted to the counting / calculating system 20, and the counting / calculating system 20 receives the information to obtain the calibration curve method or the area correction FP according to the present invention.
The concentration of the element to be analyzed is calculated by the method. The result calculated by the counting / calculation system 20 is transmitted to the input / output system 21 and displayed on the CRT or the like constituting the input / output system. Examples carried out by using the X-ray fluorescence analyzer having the above structure will be shown below together with comparative examples. Before showing examples and comparative examples,
The analytical conditions used in Examples and Comparative Examples are shown below.

First, the analytical sample will be described. Generally, the analytical error in fluorescent X-ray analysis is defined by the difference between the analytical value obtained by fluorescent X-ray analysis and the analytical value obtained by chemical analysis. However, in the local analysis in the steel material to which the present invention is applied, it is difficult to extract only the second phase in the local visual field and then perform the chemical analysis. Therefore,
In order to show that the analysis error is reduced by the method according to the present invention as compared with the conventional method, a bulk sample without the second phase (infinite thickness with respect to X-ray) is used as a sample in the examples.

Table 1 shows the calculation conditions of the theoretical X-ray fluorescence intensity used in Examples and Comparative Examples, and Table 2 shows the measurement conditions of the X-ray fluorescence intensity. In the measurement conditions shown in Table 2, the counting time is changed for each primary collimator diameter in order to keep the total number of fluorescent X-ray counts substantially constant.

[0050]

[Table 1]

[0051]

[Table 2]

With respect to the Cr—Fe binary lump sample, the theoretical strength of CrKα rays (normalized by the theoretical strength of pure Cr) was calculated using the equation (14) under the conditions shown in Table 1 and under the conditions shown in Table 2. The results of the measurement are shown in FIG. The vertical axis is CrKα
Shows the relative intensity of the line, unitless. The horizontal axis represents the Cr content (%) in the block sample. Since the CrKα ray is excited not only by the incident X-ray but also by the FeKα ray excited by the incident X-ray, as shown in FIG.
The "CrKα ray intensity" relationship curve becomes an upwardly convex asymmetric hyperbola.

With respect to the Fe-Ni binary lump sample, the theoretical intensity of FeKα rays (normalized by the theoretical intensity of pure Fe) was calculated using the equation (14) under the conditions shown in Table 1 and under the conditions shown in Table 2. FIG. 4 shows the results of the measurement. The vertical axis is FeKα
Shows the relative intensity of the line, unitless. The horizontal axis represents the Fe content (%) in the block sample. Since the FeKα ray is excited not only by the incident X-ray but also by the NiKα ray excited by the incident X-ray, as shown in FIG.
The FeKα ray intensity relation curve is an asymmetric hyperbola that is convex upward, as in FIG.

In FIGS. 3 and 4, the curve shown by the solid line has a primary collimator diameter of 5000 μm, the curve shown with a broken line has a primary collimator diameter of 100 μm, and the curve shown by the one-dot chain line has a primary collimator diameter of 30 μm. The calculated value of the fluorescent X-ray theoretical intensity in the case of is shown. Also ○
When the primary collimator diameter is 5000 μm,
The value indicated by △ is the value when the primary collimator diameter is 100 μm,
The values indicated by □ are the measured values of the fluorescent X-ray intensity when the primary collimator diameter is 30 μm.

The following can be read from the graphs shown in FIGS. (1), primary collimator diameter is from 5000μm to 100μ
When it is reduced to m, the degree of convexity is slightly increased, and when the primary collimator diameter is 30 μm, it is considerably increased. This is because as the diameter of the primary collimator decreases, the contribution of fluorescent X-rays generated from the sample surface other than the X-ray irradiation part increases. (2), the measured intensity is almost the same as the theoretical intensity predicted from the equation (14). This shows that Equation 14 is correct. Therefore, it is understood that the FP method using the equation (14) (that is, the area correction FP method according to the present invention) can be applied to the local analysis up to 30 μmφ.

Next, the relationship between the result calculated using the mathematical expression 2 (conventional theoretical formula of fluorescent X-ray intensity) and the actually measured value will be shown. FIG. 5 shows the result of calculating the theoretical intensity of CrKα rays generated from the same Cr—Fe-based sample as shown in FIG. 3 using the equation 2 and the result of actual measurement under the measurement conditions shown in Table 2. It is a graph. FIG. 6 shows the same Fe-Ni as FIG.
3 is a graph showing a result of calculating the theoretical intensity of FeKα rays generated from a system sample by using Equation 2 and a result of actual measurement under the measurement conditions shown in Table 2. 5 and FIG. 6, FIG. 5 corresponds to FIG. 3 and FIG. 6 corresponds to FIG. 4, and the meanings of the symbols shown in the figures are the same as in FIG. 3 or FIG. In addition, when the calculation is performed using the equation (2), the calculation results are all the same regardless of the size of the primary collimator diameter. Therefore, the broken line as shown in FIGS. 3 and 4 (primary collimator diameter 100 μm)
And the curve of the alternate long and short dash line (primary collimator diameter 30 μm) overlaps the solid line showing the case where the primary collimator diameter is 5000 μm. Therefore, in FIG. 5 and FIG. 6, only one curve indicated by the solid line shows the theoretical calculated value of the fluorescent X-ray. In FIG. 5 and FIG. 6, when the primary collimator diameter is 5000 μm, the measured intensity and the theoretical intensity calculated from the equation 2 are in good agreement, but the primary collimator diameter is 100 μm and 30 μm.
As m becomes smaller, the measured value deviates from the theoretically calculated value. Especially, when the primary collimator diameter decreases to 30 μm, the degree of the deviation becomes remarkable. This is 30
In the local analysis of μmφ to 100 μmφ, the contribution of the fluorescent X-ray generated from the so-called wraparound area on the sample surface around the X-ray irradiation part has been ignored in the conventional theoretical formula of fluorescent X-ray intensity (Equation 2). by.

In FIGS. 3 to 6 described above, when the primary collimator diameter is 5000 μm, the FP method using the equation 14 or the FP method using the equation 2 is almost the same in relation to the measured value. It shows the accuracy. However, when the primary collimator diameter becomes 100 μm or 30 μm,
When the formula 14 is used, the measured value and the theoretical calculated value are in good agreement and the accuracy of the formula 14 is proved, but when the formula 2 is used, the measured value and the theoretical calculated value are different from each other. , The measured value is larger. Turning it inside out, in FIG. 5 (FIG. 6), comparing the Cr (Fe) content indicated by the actual measurement value and the theoretical calculation value when the CrKα (FeKα) strength is constant, the theoretical calculation is clear. The content rate according to (the curve shown by the solid line) is higher. Therefore, the number 14
Chemical analysis of the analysis value by the fluorescent X-ray analysis method using the formula and the analysis value when the formula 2 is used (here, ICP
Compared with the analysis value by solution analysis by emission spectroscopy, the analysis value in the case of the formula 14 and the chemical analysis value are in good agreement, but the analysis value in the case of using the formula 2 is better than the chemical analysis value. It can be estimated that

Tables 3 and 4 show comparisons between the analytical values by the fluorescent X-ray analysis method using the equation 14 and the method using the equation 2 and the chemical analysis method.

[0059]

[Table 3]

[0060]

[Table 4]

In Table 3, pure Cr (pure Fe) was used as a standard sample, and No. The three types of Cr-Fe (Fe
-Ni) This analysis method (numeral 14) for a binary sample
2 shows the weight fraction (wt%) of Cr (Fe) calculated by a method using a formula), the weight fraction obtained by chemical analysis, and a comparison thereof (difference between both fraction values). In Table 3, the upper row shows the analysis result of the Cr-Fe based sample, and the lower row shows the analysis result of the Fe-Ni based sample. Table 4 shows the analysis results by the conventional fluorescent X-ray analysis method (Equation 2), and the other analysis methods (conditions) are the same as those in Table 3. In Tables 3 and 4, the primary collimator diameter used in the fluorescent X-ray analysis is 30 μm.

As can be seen from Tables 3 and 4, the difference between the analytical value and the chemical analytical value when the equation 14 is used, that is, the analytical error is 0.2% even when it is large, and in most cases it is normal. It is within the analytical tolerance of 0.1%. However, when the equation 2 is used, the analysis error is 7.3% when it is small and 10.2% when it is large. As is clear from comparison between Tables 3 and 4, the conventional FP method using the equation 2 has too large an analysis error and the X-ray irradiation area is 3
Although it cannot be used for local analysis of 0 μmφ,
The area-corrected FP method according to the present invention using the equation (14) can be used within the analysis allowable error range (0.1%) for the local analysis.

As is clear from the above, according to the above-mentioned embodiment, the influence of the wraparound of fluorescent X-rays around the X-ray irradiation site in the local analysis can be correctly evaluated, so that the quantitative value can be accurately obtained. .. In addition, although the above example shows the case where the quantitative analysis is performed on the block sample,
The quantitative correction program according to the present invention can be used for quantitative determination of the film thickness of a thin film because the equation 14 is a function of not only the sample composition but also the sample thickness. Further, the quantitative correction program according to the present invention has the same fluorescence as that added to the equation (14), even for the wraparound of the fluorescent X-ray generated when the incident X-ray is not a parallel bundle strictly but has a divergence angle. This can be applied by adding the restriction on the X-ray generation area to the equation (1).

[0064]

As described above in detail, the program of the FP method according to the present invention is based on the intensity of fluorescent X-rays generated when a sample is irradiated with X-rays having good parallelism, and the composition of the irradiation site (local area) is calculated.・ FP program that enables simultaneous analysis of film thickness. In this FP method, the emission area of the fluorescent X-ray is the incident X-ray.
Paying attention to the fact that the X-ray penetration region, the primary fluorescent X-ray generation region, the secondary fluorescent X-ray generation region, and the tertiary fluorescent X-ray generation region increase in this order, and the integral giving the fluorescent X-ray intensity is calculated as the primary fluorescent X-ray generation region. If the FP method is applied to an optical system in which X-rays are converted into a microbeam through a collimator and irradiated onto a sample, the composition of the local region (30 μmφ to 100 μmφ), which has a large error in the conventional FP method program, is used. The film thickness can be analyzed accurately.

Further, the X-ray fluorescence analyzer equipped with the FP method program capable of local analysis according to the present invention inputs the fluorescence X-ray measurement intensity into the program to determine the composition / film thickness of the local region online or Can be accurately analyzed offline.

[Brief description of drawings]

FIG. 1 shows an embodiment of a fluorescent X-ray analyzer according to the present invention, (a) is a configuration diagram schematically showing an optical system of the embodiment, and (b) is an embodiment. FIG. 3 is a block diagram schematically showing a fluorescent X-ray analyzer according to the present invention.

FIG. 2 (a) is a schematic diagram showing a generation region of each fluorescent X-ray used for developing the FP method program according to the present invention, and FIG. 2 (b) develops a conventional FP method program. It is a schematic diagram which showed the parameter for calculation of each fluorescence X-ray intensity used for that purpose.

FIG. 3 is a graph showing the relationship between the Cr content, the measured value of the CrKα ray intensity, and the calculated value by the present analysis method for each primary collimator diameter in the Cr-Fe binary lump sample.

FIG. 4 is a graph showing the relationship between the Fe content, the measured value of FeKα ray intensity, and the calculated value by the present analysis method for each primary collimator diameter for an Fe—Ni binary lump sample.

FIG. 5 is a graph showing the relationship between the Cr content, the measured value of the CrKα ray intensity, and the calculated value by the conventional analysis method for each primary collimator diameter for a Cr—Fe binary lump sample.

FIG. 6 is a graph showing, for each primary collimator diameter, the relationship between the Fe content, the actual measurement value of FeKα ray intensity, and the calculation value by the conventional analysis method for the Fe—Ni binary lump sample.

FIG. 7 is a flowchart showing a calculation process of a conventional FP method program.

[Explanation of symbols]

 10 X-ray tube 11, 32 Primary collimator 11a, 33 Secondary collimator 13 Si (Li) semiconductor detector 14 Multi-channel analyzer 20 Counting / arithmetic system a Incident X-ray penetration area b Primary fluorescence X-ray generation area c Secondary fluorescence X-ray generation area D Tertiary fluorescent X-ray generation area

Claims (2)

[Claims] 1. The theoretical fluorescence of an element in an X-ray irradiation region is detected by detecting the intensity of fluorescent X-rays generated by irradiating a sample with X-rays converted into microbeams by a primary collimator and using the fundamental parameter method (FP method). In a method of analyzing the abundance of an element by calculating X-ray intensity, a finite region in which a primary to tertiary fluorescent X-ray generation region depends on the primary collimator diameter, the X-ray incident angle, and the fluorescent X-ray extraction angle. As a method, a theoretical X-ray fluorescence intensity of each element is calculated as a fluorescent X-ray analysis method for a local portion. 2. An X-ray fluorescence analysis apparatus comprising the X-ray fluorescence intensity calculation program according to claim 1 as a means for calculating the abundance of an element from the X-ray fluorescence detection intensity.